Retrieve data from first only item in for loop - ios

Question

I have a query that gets objects from the server I'm then reducing the number of objects by matching "packName" to "className" which should just give me the children of "packName".
from this i am populating an array of struct items and pulling out the data for the first index of the array.
this is fine but I'm just a bit concerned that if the number of children increases this may slow processing down. so i was wondering if there was a way to just retrieve the first item of the for loop, which is all I'm after as the query has been sorted in ascending order.
this is the function code below.
class func createHistory(packName: String, completeBlock: ((Bool) -> Void)? = nil) {
struct initialDataStruct {
var packNameStruct : String
var packIdStruct : String
var partNameStruct : String
var partIdStruct : String
var partIndexStruct : Int
}
var initialDataArray = [initialDataStruct]()
let historyClass = PFObject(className: packName)
let query = PFQuery(className: "Part")
query.includeKey("fromPack")
query.order(byAscending: "partName")
query.fromLocalDatastore()
query.findObjectsInBackground { (objects, error) in
if error != nil {
print(error!)
}
else if let parts = objects {
for object in parts {
// if the fromPack column has data
if let fromPack = object.object(forKey: "fromPack") as? PFObject {
// create the class name from the pack name
if let className = (fromPack.object(forKey: "packName") as? String) {
// packName was sent from JVC
// this will limit array items to how ever many children packName has
if packName == className {
// because its sorted could probably just get the first item here
let packName = fromPack.object(forKey: "packName") as! String
let packId = fromPack.objectId as String!
let partName = object.object(forKey: "partName") as! String
let partId = object.objectId as String!
let partIndex = 0
initialDataArray.append(initialDataStruct(packNameStruct: packName,
packIdStruct: packId!,
partNameStruct: partName,
partIdStruct: partId!,
partIndexStruct: partIndex))
}
}
}
} // for
historyClass.add(initialDataArray[0].packNameStruct, forKey: "packName")
historyClass.add(initialDataArray[0].partIdStruct, forKey: "packId")
historyClass.add(initialDataArray[0].partNameStruct, forKey: "partName")
historyClass.add(initialDataArray[0].partIndexStruct, forKey: "partIndex")
print(historyClass)
PFObject.pinAll(inBackground: [historyClass])
}
} // query
}